cbcdc22d90
(From yocto-docs rev: 0f8b655da637ebf7708bdfff1473707c9ea3b8ef) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
279 lines
17 KiB
XML
279 lines
17 KiB
XML
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<chapter id='dev-manual-start'>
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<title>Getting Started with the Yocto Project</title>
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<para>
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This chapter introduces the Yocto Project and gives you an idea of what you need to get started.
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You can find enough information to set up your development host and build or use images for
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hardware supported by the Yocto Project by reading
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<ulink url='http://www.yoctoproject.org/docs/yocto-quick-start/yocto-project-qs.html'>
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The Yocto Project Quick Start</ulink>.
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</para>
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<para>
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The remainder of this chapter summarizes what is in the Yocto Project Quick Start and provides
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some higher-level concepts you might want to consider.
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</para>
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<section id='introducing-the-yocto-project'>
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<title>Introducing the Yocto Project</title>
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<para>
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The Yocto Project is an open-source collaboration project focused on embedded Linux development.
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The project currently provides a build system, which is sometimes referred to as "Poky",
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and provides various ancillary tools suitable for the embedded developer.
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The Yocto Project also features the Sato reference User Interface, which is optimized for
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stylus driven, low-resolution screens.
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</para>
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<para>
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You can use the Yocto Project, which uses the BitBake build tool, to develop complete Linux
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images and associated user-space applications for architectures based on ARM, MIPS, PowerPC,
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x86 and x86-64.
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While the Yocto Project does not provide a strict testing framework,
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it does provide or generate for you artifacts that let you perform target-level and
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emulated testing and debugging.
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And, if you are an <trademark class='trade'>Eclipse</trademark>
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IDE user, you can install an Eclipse Yocto Plug-in to allow you to
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develop within that familiar environment.
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</para>
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</section>
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<section id='getting-setup'>
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<title>Getting Setup</title>
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<para>
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Here is what you need to get set up to use the Yocto Project:
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<itemizedlist>
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<listitem><para><emphasis>Host System:</emphasis> You should have a reasonably current
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Linux-based host system.
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You will have the best results with a recent release of Fedora,
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OpenSUSE, or Ubuntu as these releases are frequently tested against the Yocto Project
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and officially supported.
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You should also have about 100 gigabytes of free disk space for building images.
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</para></listitem>
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<listitem><para><emphasis>Packages:</emphasis> The Yocto Project requires certain packages
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exist on your development system (e.g. Python 2.6 or 2.7).
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See "<ulink url='http://www.yoctoproject.org/docs/yocto-quick-start/yocto-project-qs.html#packages'>The Packages</ulink>"
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section in the Yocto Project Quick start for the exact package
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requirements and the installation commands to install them
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for the supported distributions.</para></listitem>
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<listitem id='local-yp-release'><para><emphasis>Yocto Project Release:</emphasis>
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You need a release of the Yocto Project.
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You can get set up with local Yocto Project files one of two ways depending on whether you
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are going to be contributing back into the Yocto Project source repository or not.
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<note>
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Regardless of the method you use, this manual refers to the resulting
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hierarchical set of files as "the Yocto Project files" or "the Yocto Project file
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structure."
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</note>
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<itemizedlist>
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<listitem><para><emphasis>Tarball Extraction:</emphasis> If you are not going to contribute
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back into the Yocto Project, you can simply download the Yocto Project release you want
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from the website’s <ulink url='http://yoctoproject.org/download'>download page</ulink>.
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Once you have the tarball, just extract it into a directory of your choice.</para>
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<para>For example, the following command extracts the Yocto Project 1.1 release tarball
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into the current working directory and sets up the Yocto Project file structure
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with a top-level directory named <filename>poky-1.1</filename>:
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<literallayout class='monospaced'>
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$ tar xfj poky-1.1.tar.bz2
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</literallayout></para>
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<para>This method does not produce a Git repository.
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Instead, you simply end up with a local snapshot of the
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Yocto Project files that are based on the particular release in the
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tarball.</para></listitem>
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<listitem><para><emphasis>Git Repository Method:</emphasis> If you are going to be contributing
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back into the Yocto Project, you should use Git commands to set up a local
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Git repository of the Yocto Project files.
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Doing so creates a Git repository with a complete history of changes and allows
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you to easily submit your changes upstream to the project.</para>
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<para>The following transcript shows how to clone the Yocto Project files'
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Git repository into the current working directory.
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The command creates the repository in a directory named <filename>poky</filename>.
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For information on the Yocto Project and Git, see the
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"<link linkend='git'>Git</link>" section.
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<literallayout class='monospaced'>
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$ git clone git://git.yoctoproject.org/poky
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Initialized empty Git repository in /home/scottrif/poky/.git/
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remote: Counting objects: 107624, done.
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remote: Compressing objects: 100% (37128/37128), done.
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remote: Total 107624 (delta 73393), reused 99851 (delta 67287)
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Receiving objects: 100% (107624/107624), 69.74 MiB | 483 KiB/s, done.
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Resolving deltas: 100% (73393/73393), done.
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</literallayout></para>
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<para>For another example of how to set up your own local Git repositories, see this
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<ulink url='https://wiki.yoctoproject.org/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP'>
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wiki page</ulink>, which describes how to create both <filename>poky</filename>
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and <filename>meta-intel</filename> Git repositories.</para></listitem>
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</itemizedlist></para></listitem>
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<listitem id='local-kernel-files'><para><emphasis>Linux Yocto Kernel:</emphasis>
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If you are going to be making modifications to a supported Linux Yocto kernel, you
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need to establish local copies of the source.
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This setup involves creating a bare clone of the Linux Yocto kernel and then cloning
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that repository.
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You can create the bare clone and the copy of the bare clone anywhere you like.
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For simplicity, it is recommended that you create these structures outside of the
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Yocto Project files' Git repository.</para>
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<para>As an example, the following transcript shows how to create the bare clone
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of the <filename>linux-yocto-3.0</filename> kernel and then create a copy of
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that clone.
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<note>When you have a local Linux Yocto kernel Git repository, you can
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reference that repository rather than the upstream Git repository as
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part of the <filename>clone</filename> command.
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Doing so can speed up the process.</note>
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In the following example, the bare clone is named
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<filename>linux-yocto-3.0.git</filename>, while the
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copy is named <filename>linux-yocto-3.0</filename>:
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<literallayout class='monospaced'>
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$ git clone --bare git://git.yoctoproject.org/linux-yocto-3.0 linux-yocto-3.0.git
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Initialized empty Git repository in /home/scottrif/poky/linux-yocto-3.0.git/
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remote: Counting objects: 1886034, done.
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remote: Compressing objects: 100% (314326/314326), done.
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remote: Total 1886034 (delta 1570200), reused 1870337 (delta 1554798)
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Receiving objects: 100% (1886034/1886034), 401.51 MiB | 3.27 MiB/s, done.
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Resolving deltas: 100% (1570200/1570200), done.
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</literallayout></para>
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<para>Now create a clone of the bare clone just created:
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<literallayout class='monospaced'>
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$ git clone linux-yocto-3.0.git linux-yocto-3.0
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Initialized empty Git repository in /home/scottrif/poky/linux-yocto-3.0/.git/
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Checking out files: 100% (35188/35188), done.
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</literallayout></para></listitem>
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<listitem id='poky-extras-repo'><para><emphasis>
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The <filename>poky-extras</filename> Git Repository</emphasis>:
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The <filename>poky-extras</filename> Git repository contains metadata needed to
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build the kernel image.
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In particular, it contains the kernel <filename>.bbappend</filename> files that you
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edit to point to your locally modified kernel source files and to build the kernel
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image.
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Pointing to these local files is much more efficient than requiring a download of the
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source files from upstream each time you make changes to the kernel.</para>
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<para>It is good practice to create this Git repository inside the Yocto Project
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files Git repository.
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Following is an example that creates the <filename>poky-extras</filename> Git
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repository inside the Yocto Project files Git repository, which is named
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<filename>poky</filename> in this case:
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<literallayout class='monospaced'>
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$ cd ~/poky
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$ git clone git://git.yoctoproject.org/poky-extras poky-extras
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Initialized empty Git repository in /home/scottrif/poky/poky-extras/.git/
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remote: Counting objects: 531, done.
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remote: Compressing objects: 100% (471/471), done.
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remote: Total 531 (delta 138), reused 307 (delta 39)
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Receiving objects: 100% (531/531), 517.86 KiB, done.
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Resolving deltas: 100% (138/138), done.
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</literallayout></para></listitem>
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<listitem><para><emphasis>Supported Board Support Packages (BSPs):</emphasis>
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Similar considerations exist for BSPs.
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You can get set up for BSP development one of two ways: tarball extraction or
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with a local Git repository.
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Regardless of the method you use, the Yocto Project uses the following BSP layer
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naming scheme:
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<literallayout class='monospaced'>
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meta-<BSP_name>
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</literallayout>
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where <BSP_name> is the recognized BSP name.
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Here are some examples:
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<literallayout class='monospaced'>
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meta-crownbay
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meta-emenlow
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meta-n450
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</literallayout>
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<itemizedlist>
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<listitem><para><emphasis>Tarball Extraction:</emphasis> You can download any released
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BSP tarball from the same
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<ulink url='http://yoctoproject.org/download'>download site</ulink> used
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to get the Yocto Project release.
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Once you have the tarball, just extract it into a directory of your choice.
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Again, this method just produces a snapshot of the BSP layer in the form
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of a hierarchical directory structure.</para></listitem>
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<listitem><para><emphasis>Git Repository Method:</emphasis> If you are working
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with a Yocto Project files Git repository, you should also set up a
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<filename>meta-intel</filename> Git repository.
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Typically, you set up the <filename>meta-intel</filename> Git repository inside
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the Yocto Project files Git repository.</para>
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<para>For example, the following transcript shows the steps to clone the
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<filename>meta-intel</filename>
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Git repository inside the <filename>poky</filename> Git repository.
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<literallayout class='monospaced'>
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$cd poky
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$ git clone git://git.yoctoproject.org/meta-intel.git
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Initialized empty Git repository in /home/scottrif/poky/meta-intel/.git/
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remote: Counting objects: 1325, done.
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remote: Compressing objects: 100% (1078/1078), done.
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remote: Total 1325 (delta 546), reused 85 (delta 27)
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Receiving objects: 100% (1325/1325), 1.56 MiB | 330 KiB/s, done.
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Resolving deltas: 100% (546/546), done.
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</literallayout></para>
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<para>The same
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<ulink url='https://wiki.yoctoproject.org/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP'>
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wiki page</ulink> referenced earlier covers how to
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set up the <filename>meta-intel</filename> Git repository.</para></listitem>
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</itemizedlist></para></listitem>
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<listitem><para><emphasis>Eclipse Yocto Plug-in:</emphasis> If you are developing
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applications using the Eclipse Integrated Development Environment (IDE),
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you will need this plug-in.
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See the
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"<ulink url='http://www.yoctoproject.org/docs/adt-manual/adt-manual.html#setting-up-the-eclipse-ide'>Setting up the Eclipse IDE</ulink>"
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section in the Yocto Application Development Toolkit (ADT)
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User’s Guide for more information.</para></listitem>
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</itemizedlist>
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</para>
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</section>
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<section id='building-images'>
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<title>Building Images</title>
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<para>
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The build process creates an entire Linux distribution, including the toolchain, from source.
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For more information on this topic, see the
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"<ulink url='http://www.yoctoproject.org/docs/yocto-quick-start/yocto-project-qs.html#building-image'>Building an Image</ulink>"
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section in the Yocto Project Quick Start.
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</para>
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<para>
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The build process is as follows:
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<orderedlist>
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<listitem><para>Make sure you have the Yocto Project files as described in the
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previous section.</para></listitem>
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<listitem><para>Initialize the build environment by sourcing a build environment
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script.</para></listitem>
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<listitem><para>Optionally ensure the <filename>conf/local.conf</filename> configuration file is set
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up how you want it.
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This file defines the target machine architecture and other build options.</para></listitem>
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<listitem><para>Build the image using the BitBake command.
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If you want information on Bitbake, see the user manual at
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<ulink url='http://docs.openembedded.org/bitbake/html'></ulink>.</para></listitem>
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<listitem><para>Run the image either on the actual hardware or using the QEMU
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emulator.</para></listitem>
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</orderedlist>
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</para>
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</section>
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<section id='using-pre-built-binaries-and-qemu'>
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<title>Using Pre-Built Binaries and QEMU</title>
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<para>
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Another option you have to get started is to use pre-built binaries.
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This scenario is ideal for developing software applications to run on your target hardware.
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To do this, you need to install the stand-alone Yocto Project cross-toolchain tarball and
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then download the pre-built kernel that you will boot in the QEMU emulator.
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Next, you must download and extract the target root filesystem for your target
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machine’s architecture.
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Finally, you set up the environment to emulate the hardware and then start the QEMU emulator.
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</para>
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<para>
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You can find details on all these steps in the
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"<ulink url='http://www.yoctoproject.org/docs/yocto-quick-start/yocto-project-qs.html#using-pre-built'>Using Pre-Built Binaries and QEMU</ulink>"
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section of the Yocto Project Quick Start.
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</para>
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</section>
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</chapter>
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